Select expected remote libc++ library name based on remote platform.

Select expected remote libc++ library name based on remote platform. This is
used to verify libc++ is in the loaded image list by various tests which use it.

Test Plan:
Passes the following tests mac -> linux with this patch:
TestDataFormatterLibccIterator.py
TestDataFormatterLibccMap.py
TestDataFormatterLibccMultiMap.py
TestDataFormatterLibcxxMultiSet.py
TestDataFormatterLibcxxSet.py
TestDataFormatterUnordered.py

Differential Revision: http://reviews.llvm.org/D9759

llvm-svn: 237288

lldb/test/lldbtest.py

@@ -1836,7 +1836,7 @@ def getLLDBLibraryEnvVal(self):
             return self.lib_dir
 
     def getLibcPlusPlusLibs(self):
-        if sys.platform.startswith('freebsd') or sys.platform.startswith('linux'):
+        if self.getPlatform() == 'freebsd' or self.getPlatform() == 'linux':
             return ['libc++.so.1']
         else:
             return ['libc++.1.dylib','libc++abi.dylib']